Thread-cutting mechanism for sewing machine

ABSTRACT

A thread-cutting apparatus for use on a sewing machine and including a horizontally disposed clipper mechanism positioned transversely of the line of movement of articles through the machine and rearwardly of the stitch-forming mechanism substantially in the plane of the machine&#39;&#39;s work support and needle plates. A suction nozzle is positioned beneath an opening in the work support plate, and extends forwardly of the cutting teeth on the clipper blades to draw a chain of stitches into the cutting mechanism to cut a chain adjacent the trailing edge of an article sewn on the machine and again adjacent the leading edge of a subsequent article sewn on the machine. The top blade of the clipper is fixed and forms a continuation of the work support surface defined by the needle plate and work support.

United States Patent [72} inventor George B. Armstead, Jr.

Glastonbury, Conn. [21 I Appl. No. 376,898 [22] Filed June 22, 1964 [45] Patented Jan. 26, 1971 [73] Assignee The Merrow Machine Company Hartlord, Conn. a corporation of Connecticut [54] THREAD-CUTTING MECHANISM FOR SEWING MACHINE 9 Claims, 7 Drawing Figs.

[52] US. Cl 112/252 [51] Int. Cl D05b 65/06 [50] Field of Search 1 12/252, (Suction Digest); 26/7 [56] References Cited UNITED STATES PATENTS 2,356,378 8/1944 Capolupo 26/7 2,712,805 7/1955 Peterson et a1. 112/252 3,058,438 10/ l 962 Russell et al 112/252 3,109,399 11/1963 Hornberger, Sr.. 1 12/252 3,182,620 5/1965 Hornberger 1 12/252 Primary Examiner-James R. Boler Attorney-Beveridge & DeGrandi ABSTRACT: A thread-cutting apparatus for use on a sewing machine and including a horizontally disposed clipper mechanism positioned transversely of the line of movement of articles through the machine and rearwardly of the stitchforming mechanism substantially in the plane of the machines work support and needle plates. A suction nozzle is positioned beneath an opening in the work support plate, and extends forwardly of the cutting teeth on the clipper blades to draw a chain of stitches into the cutting mechanism to cut a chain adjacent the trailing edge of an article sewn on the machine and again adjacent the leading edge of a subsequent article sewn on the machine. The top blade of the clipper is fixed and forms a continuation of the work support surface defined by the nee dle plate and work support.

.liil

PATENTED JAMES 197:

SHEET 1 0F 3 GEORGE B. ARMSTEAD, JR.

PATEN TEUJMsIQfl SHEET 2 UF 3 INVENTOR.

GEORGE B ARMSTEAD,JR.

PATENTEUJAN26I97I 3,657,730

sum 3 OF 3 I NVENTOR.

BY hwnw y GEORGE B. ARMSTEAD, JR.

THREAD-CUTTING MECHANISM FOR SEWING MACHINE This invention relates to thread-cutting mechanisms, and more particularly to a thread-cutting mechanism for use with a sewing machine for automatically removing the chain of stitches formed between successive articles on the machine.

In the production of knitted articles such as hosiery, it is common practice to knit the hosiery on a circular knitting apparatus, leaving an elongated openingacross the toe. This opening is subsequently closed by passing the individual hose successively through a sewing machine which trims off excess material and joins the opposite edges of the opening with an over-the-edge stitch which permits the seam thus formed to be flattened. The sewing machine forms a continuous chain of stitches so that the hose which are passed through the machine, are joined by a length of the chain of stitches extending between the successive hose. This chain of stitches joining the hose must be removed before the stockings can be further processed and marketed.

Numerous attempts have been made to provide a cutting mechanism for machines of this type to automatically remove the chain of stitches between articles, but these devices have not been entirely satisfactory and it is not uncommon for the operator to manually remove the chain of stitches by use of scissors.

In the removal of excess thread chain, it is desirable that the chain be cut as closely adjacent the articles stitched as is prac ticable, preferably leaving only one or two stitches adjacent each end of the seam to prevent raveling. However, this has not been practical with the prior art'cutters or with scissors, and the excess length of chain was not only uncomfortable to the wearer, but also presented an unsightly appearance, thereby reducing the marketability of the articles.

It is the primary object of this invention to provide an improved thread-cutting mechanism for removing the chain of thread between articles successively stitched on a sewing machine.

Another object is to provide an improved thread-cutting mechanism for removing the chain of thread between articles successively stitched on a sewing machine by clipping the chain closely adjacent the trailing edge of leading articles and again closely adjacent the leading edge of the following article.

Another object is to provide such a mechanism which will remove the chain of stitches without excessive and unnecessary cutting of the chain. 7

In the attainment of the foregoing and other objects, an important feature of the invention resides in providing a horizontally disposed clipper mechanism positioned transversely of the line of movement of articles passed through the sewing machine, at a point spaced rearwardly from the stitchforming mechanism and substantially in the plane of the work support platform of the sewing machine. A suction mechanism having a suction tube extending beneath the work plate terminates in an upwardly directed inlet orifice positioned below the clipper mechanism at a point spaced betweenthe clipper and the stitch-forming station so that, as the trailing edge of a stitched article such as a stocking passes over the open inlet orifice of the suction tube, the chain of stitches will be drawn downwardly into the tube and, as the stocking moves rearwardly, the chain will be pulled into the clipper mechanism to be cut closely adjacent the trailing edge of the stocking. Once the chain has been cut, it will extend into the vacuum tube, clear of the clipper mechanism, until the leading edge of the subsequently stitched article passes over the tube and the chain is again pulled into the clipper mechanism to be cut closely adjacent the leading edge of the subsequently formed article. Since the top surface of the cutter mechanism is substantially coplanar with the top of the work support plate, the cutter mechanism offers no obstruction to movement of the stockings through the machine.

Other and further objects and advantages of the machine will become apparent from the following detailed description taken in conjunction with drawings in which:

FIG. I is an end elevation view of a sewing machine including the improved thread-cutting mechanism according to the present invention;

FIG. 2 is a top plan view of the device shown in FIG. 1;

FIG. 3 is a fragmentary sectional view taken on line 3-3 of FIG. 4; a

FIG. 4 is a fragmentary side elevation view of a portion of the device shown in FIG. 1;

FIG. 5 is a sectional view taken on line 5-5 of FIG. 4 and showing the clipper mechanism assembled;

FIG. 6 is a fragmentary view showing the eccentric drive for the clipper mechanism; and,

FIG. 7 is an exploded view of the clipper mechanism shown in FIG. 5.

Referring now to the drawings in detail, a sewing machine embodying the thread-cutting mechanism according to this invention illustrated generally by the numeral 10, includes a work plate 12 pivotally mounted, as by pin 14, to a work plate support block 16. Work plate 12 provides a support for articles (not shown) which are to be stitched by the machine as they are moved by feed mechanism 18 past a stitch-forming station illustrated generally by the numeral 20. Work support plate 12 has a flat substantially horizontal upper surface 22 extending from a point in front of the stitch-forming station to a position rearward from the stitch-forming station to provide a continuous support for the articles as they are passed through the machine. Plate 12 has a cutout portion, or opening, 23 to receive a clipper mechanism described below.

The thread chain cutting mechanism according to this invention includes a horizontally disposed clipper mechanism 26 positioned transversely to the path of movement of articles through the machine. The clipper mechanism includes an upper blade 28 having a plurality of teeth 30 formed in its forward edge, and a lower blade 32, also having a plurality of teeth 34 on its forward edge, slidablymounted on the underside of blade 28. Blade 28 is fixedly secured within opening 23, as by bolt 36 extending into support block 16, and suitable shims 38 may be used to position the top surface 40 vertically with respect to surface 22 so that the clipper mechanism effectively forms a continuation of work plate 12 with the clipper mechanism offering a minimum of resistance to articles moving through the machine. An elongated keyway 42, formed in the underside of blade 28, receives and positions a key 44 which acts as a track, or guide, for a complementary keyway 46 formed in the top surface of blade 32 to guide blade 32 in its reciprocal movement with respect to blade 28.

Blade 32 is movably mounted on blade 28 by a pin 50 extending through an elongated slot 52 in blade 32 and threaded into an opening 54 in blade 28. Suitable means, such as setscrew 56 prevents pin 50 from working loose during operation of the clipper mechanism. Blade 32 is urged into sliding, cutting contact with blade 28 by a Belleville spring washer 58, as shown in FIG. 5.

The upper surface of blade 28 is curved, as at 60, to provide a smooth transition between the leading edge and top surface to provide a minimum of obstruction to articles passing through the machine. Also, blade 28 extends slightly forward from blade 32, as at 62 to eliminate any possibility of the stitched article being cut by the clipper.

To move blade 32 reciprocably along track 44, a shaft 64 is rotatably mounted as by journals 66 in an opening 68 in support block 16. An arm 70, rigidly mounted on the end of shaft 64 and projecting radially therefrom, has its radially outer end positioned within a slot 72 on the under side of blade 32. Arm 70 is caused to move in an arcuate path by oscillation of shaft 64 about its longitudinal axis. Shaft 64 is oscillated by a rod 76 eccentrically connected, as by spherical bearing 78 to shaft 64, with rod 76 extending in a direction substantially perpendicular to the longitudinal axis of shaft 64. Rod 76 is reciprocated along its longitudinal axis by an electric motor 80 acting through an eccentric bearing 82 carried on the end of drive shaft 83. Motor 80 is supported on the back of sewing machine 10 by suitable mounting brackets 84 and bolts 86. A separate control switch, not shown permits the cutting mechanism to be operated independently of the drive means for the sewing machine. 7

To assure that the chain of stitches between successive articles is cut by the clipper mechanism, an elongated suction tube 90, connected to a suitable vacuum source (not shown) by a flexible hose 92, is positioned below the clipper to draw the chain into the cutting teeth. Tube 90 terminates in an open inlet orifice 94 positioned below the cutting teeth 3'1), 34 and extends forwardly therefrom in the direction of the stitchforrning station 20. Tube 90'is retained in position by suitable clamp means 96 mounted on the back of the sewing machine.

From the above it can be seen that as articles, supported on work plate 12, are fed through the machine by feeding mechanism 18, the successive articles and the chain of stitches, will pass over the top surface of the fixed blade 28 of the clipper mechanism. By applying a vacuum to the suction tube 90, the chain of stitches extending from the trailing edge of a stitched article toward the stitch-fuming station will be drawn downwardly into the open inlet orifice 94 of tube 90 and, thereby, be pulled into engagement with the cutting teeth of the clipper mechanism 26. Once the chain of stitches has been cut adjacent the trailing edge of the first stitched article, the chain will then extend in line from the stitch-forming station over the forward edge of orifice 94 and into tube 90. When a subsequent article is fed through the machine, this chain of stitches will be carried rearwardly, and as the leading edge of the stitched article passes above the cutting teeth of clipping mechanism 26, the chain will again be cut closely adjacent this leading edge. Thus, the length of chain extending between the two articles is positively removed closely adjacent each of the articles without continuous clipping or cutting of the chain, thereby greatly facilitating the collection of the waste material removed and greatly reducing the lint produced by the cutting mechanism Since the top blade of the clipping mechanism is fixed and has its top surface substantially coplanar with the surface of the work-supporting plate, articles passing through the sewing machine are supported in a substantially flat smooth condition as they pass over the clipping mechanism. This greatly facilitates cutting and removing of the thread chain, and permits the chain to be clipped closely adjacent the article, leaving only a minimum of the chain required to prevent raveling.

By employing a separate motor drive, the cutting mechanism can be installed on existing high-speed industrial sewing machines without necessitating I excessive modifications of the machine. Also, the clipper mechanism can be operated at a speed much slower than if directly driven by the high-speed machine drive, thereby eliminating the necessity for expensive speed reduction equipment. Further, the cutting mechanism may be selectively operated at the will of the machine operator, depending upon the requirements of the particularjob being performed on the machine.

While I have described and illustrated a preferred embodiment of my invention, I wish it understood that I do not intend to be restricted solely thereto, but that I do intend to cover all embodiments thereof which would be apparent to one skilled in the art and which come within the spirit and scope of my invention.

I claim:

11. In a sewing machine including, in combination a stitchforming mechanism, a feeding mechanism for feeding articles past said stitch-forming mechanism for forming a continuous chain of stitches in and between successive articles sewn on the machine, a work support surface defined by a needle plate and a work support plate, and a thread-cutting mechanism for removing said chain of stitches between successive articles, the improvement wherein said thread-cutting mechanism comprises, an opening in said work support surface rearwardly of said stitch-forming mechanism, an orifice disposed beneath said opening and connected to a source of vacuum for drawing said chain of stitches between successive articles through said opening and into said orifice, and a clipper assembly including a pair of relatively movable, substantiallyhorizontal, toothed blades mounted within sald opening and disposed transversely of the path of movement of articles through the machine to sever chains of stitches drawn through said opening, the top blade of said pair of toothed blades being fixed and having its top surface positioned to form a continuation of said work support surface to support an article passing over said openmg.

2. The sewing machine as defined in claim 1 wherein said clipper mechanism is spaced rearwardly from the forward edge of said opening and overlies a portion of said orifice with said orifice extending forwardly therefrom in the direction of the stitch forming mechanism.

3. The sewing machine as defined in claim 2 and further comprising means operating said clipper mechanism independently of the feeding and stitch-forming mechanisms.

4. An apparatus of the character described which comprises in combination; a sewing needle; means for feeding a workpiece to the needle so as to effect a stitching operation; a surplus thread-removing cutter unit having a horizontally disposed blade provided with a cutting area defining surface portion arranged in interposed substantially coplanar relation along a horizontal path of travel of the workpiece beyond the location where the stitching operation is performed and in such manner as to enable the workpiece to be contactingly moved along said surface portion; and means for effecting operation of said cutting unit.

5. An apparatus in accordance with claim 4, which includes suction means arranged below the cutter unit and adapted to effect disposal of the surplus thread severed by the cutter unit to a location remote from the latter.

6. An apparatus in accordance with claim 4, which includes a surplus thread-receiving suction nozzle having a thread-entering portion of substantially trough-shaped configuration that is positionally arranged directly below said cutter unit so as to effect drawing of the surplus thread into the latter.

7. An apparatus of the character described which comprises in combination; a sewing needle; means for feeding a workpiece to the needle so as to effect a stitching operation; a surplus thread-removing cutter unit which includes a lower horizontally disposed, reciprocably operable toothed blade, and an upper horizontally disposed stationarily mounted toothed blade having a top surface portion arranged in interposed substantially coplanar relation along the path of travel of the workpiece, said top surface of said upper blade being positioned beyond the location where the stitching operation is performed and in such manneras to enable the workpiece to be contactingly moved along said top surface; and means for effecting reciprocation of said lower blade so as to effect cutting of the surplus thread by the cutter unit.

8. An apparatus in accordance with claim 7, which includes a surplus thread-receiving suction nozzle having a thread-entering portion of substantially trough-shaped configuration that is positionally arranged below the reciprocably operable tooth blade of said cutter unit so as to effect drawing of the surplus thread into the latter.

9. An apparatus in accordance with claim 7, wherein the tips of the teeth of said tooth blades are blunted. 

1. In a sewing machine including, in combination a stitchforming mechanism, a feeding mechanism for feeding articles past said stitch-forming mechanism for forming a continuous chain of stitches in and between successive articles sewn on the machine, a work support surface defined by a needle plate and a work support plate, and a thread-cutting mechanism for removing said chain of stitches between successive articles, the improvement wherein said thread-cutting mechanism comprises, an opening in said work support surface rearwardly of said stitch-forming mechanism, an orifice disposed beneath said opening and connected to a source of vacuum for drawing said chain of stitches between successive articles through said opening and into said orifice, and a clipper assembly including a pair of relatively movable, substantially horizontal, toothed blades mounted within said opening and disposed transversely of the path of movement of articles through the machine to sever chains of stitches drawn through said opening, the top blade of said pair of toothed blades being fixed and having its top surface positioned to form a continuation of said work support surface to support an article passing over said opening.
 2. The sewing machine as defined in claim 1 wherein said clipper mechanism is spaced rearwardly from the forward edge of said opening and overlies a portion of said orifice with said orifice extending forwardly therefrom in the direction of the stitch forming mechanism.
 3. The sewing machine as defined in claim 2 and further comprising means operating said clipper mechanism independently of the feeding and stitch-forming mechanisms.
 4. An apparatus of the character described which comprises in combination; a sewing needle; means for feeding a workpiece to the needle so as to effect a stitching operation; a surplus thread-removing cutter unit having a horizontally disposed blade provided with a cutting area defining surface portion arranged in interposed substantially coplanar relation along a horizontal path of travel of the workpiece beyond the location where the stitching operation is performed and in such manner as to enable the workpiece to be contactingly moved along said surface portion; and means for effecting operation of said cutting unit.
 5. An apparatus in accordance with claim 4, which includes suction means arranged below the cutter unit and adapted to effect disposal of the surplus thread severed by the cutter unit to a location remote from the latter.
 6. An apparatus in accordance with claim 4, which includes a surplus thread-receiving suction nozzle having a thread-entering portion of substantially trough-shaped configuration that is positionally arranged directly below said cutter unit so as to effect drawing of the surplus thread into the latter.
 7. An apparatus of the character described which compriSes in combination; a sewing needle; means for feeding a workpiece to the needle so as to effect a stitching operation; a surplus thread-removing cutter unit which includes a lower horizontally disposed, reciprocably operable toothed blade, and an upper horizontally disposed stationarily mounted toothed blade having a top surface portion arranged in interposed substantially coplanar relation along the path of travel of the workpiece, said top surface of said upper blade being positioned beyond the location where the stitching operation is performed and in such manner as to enable the workpiece to be contactingly moved along said top surface; and means for effecting reciprocation of said lower blade so as to effect cutting of the surplus thread by the cutter unit.
 8. An apparatus in accordance with claim 7, which includes a surplus thread-receiving suction nozzle having a thread-entering portion of substantially trough-shaped configuration that is positionally arranged below the reciprocably operable tooth blade of said cutter unit so as to effect drawing of the surplus thread into the latter.
 9. An apparatus in accordance with claim 7, wherein the tips of the teeth of said tooth blades are blunted. 